Purpose: 1. To identify the receptors on malaria parasites for red cell invasion and on infected red cells for adhesion to endothelium and to placenta. 2. To identify the red cell ligands for each parasite receptor. 3. To identify the minimal domain in the variant antigen for binding to placenta. 4. Test a region on the variant antigen for inducing protection against P. falciparum in Aotus monkeys and for overcoming variation. 5. Identify P. falciparum proteins that induce antibodies to block infection. [unreadable] Accomplishments during the year: 1. Rhomboid, an intramembrane protease that cleaves parasite receptors, has been identified. 2. The sialic acid binding site has been identified on BAEBL, a parasite receptor.